High-frequency cable



Filed Dec. 20, 1935 Patented Aug. v6, 1940 UNITED STATES PATENT OFFICEHIGH-FREQUENCY CABLE Walter Max Hahnemann,

Berlin-Marienfelde,

Germany, assignor to G. Lorenz Aktiengesellschaft, Berlin-Tempelhof,Germany, a company I Claims.

It is well known that the transmission over cables of electrical energyfor communication purposes may be carried out by means of high frequencyalternating currents. The cables used 5 to such end are either so-calledconcentric cables, i. e., cables having coaxial conductors, or are ofthe type in which the conductors are parallel with each other, that is,arranged aside one another. Equally, constructions of such cables areknown which mainly aim at requiring the least possible expenditure ininsulating material in order that the mutulal capacity of the conductorsand hence losses within the cable shall be as low as possible.

The invention likewise proceeds from this consideration. It relates totwo-core cables and makes use of flat or strap-shaped conductors, thatis, conductors which are not of a circular or similar cross-sectionalarea.

In this way it is possible owing to the skin-effeet to employ cables ofa two-core type, that is,

not of the concentric type, without the resistance becoming too great.With cable cores circular in cross-section the current distribution overthe cross-sectional area is only appropriate if the cable is aconcentric one, that is to say, is not appropriate in the two-core case.

The conductors or cores in cables as provided by the invention are soarranged with respect to each other as to ensure that the mutualcapacity is as low as possible.

Some embodiments of the invention are described hereafter with referenceto the accompanying drawing in which--- I v Fig. 1 in a cross-sectionthrough the conductor arrangement illustrates the simplest embodiment.Fig. 2 is a diagram relating to the mode of action of the novelarrangement. Figs. 3 and 3a are views of the two conductors of a deviceaccording to Fig. 1. Fig. 4 is a somewhat diagrammatic perspective viewof a device consisting of the two conductors represented in Figs. 3 and3a.

Fig. 5 is a representation similar to Fig. 4 and illustrates thecompleted state of the device shown there. Fig. 6 is a sectional view ofa further development of the device represented in Fig. 5. Fig. 7 showsa section on the line 1-1 of Fig. 6. Fig. 8 is a sectional viewillustrating a modification of the arrangement represented in Figs. 6and -'7.. Fig. 9 is a sectional diagrammatic view of a multiple cableformed of a plurality of cross-shaped conductors.

The arrangement according to Fig. 1 consists of two fiat or strap-shapedconductors I, 2 whichconstitute the two-core arrangement, one

of them being a'return conductor. These two conductors are arranged tointersect lengthwise at right angles, so that the arrangement formed inthis way is cross-shaped'in cross-section.

By this fundamental arrangement, with the 5 least possible resistancethe 'most favorable current distribution and the least possible capacitybetween the conductors is attained owing to the skin efiect.

Such cross-shape of a two-core arrangement 10 has the advantage that thecross-sectional area is utilized in a particularly advantageous manner,since the skin efiect causes the high frequency currents to flow only onthe surface facing the field. Due to the cross-shape also the 1 currentdistribution is very advantageous. It can be ascertained in this regardthat the current distribution which occurs in the arrangement shown inFig. 1, in consequence of the field displacement that will arrive isabout of the form of curve represented inFig. 2 and is so with respectto both sides of the conductor surface,

Arrangements according to Fig. 1 may be accomplished in the mannerappearing from Figs; 3 to 5. The strap-shaped conductor I here has slotsI. The strap-shaped conductor 2 is made in two parts 8, 9. These areprovided with tongues b, 0 adapted to be inserted in the slots 1, sothat the parts I, 8, 9 can be assembled in the manner obvious from Figs.4 or 5. The tongues 11, c are 0 then fixed to each other, as by rivetingor spot welding, or in any other suitable manner. The mutual insulationof the conductors I, 2 may be effected by means of pieces I2 inserted inthe slots 1, as indicated in Figs. 4 and 5.

In order to secure the conductors I, 2 in their mutual position, theyare preferably provided with notches Ill in their edges and securingmeans of .an insulating material are. disposed in these notches.

Such notches are shown in Figs. 40 5 to 8.

The securing means may consist in rings II, as shown in Figs. 5 to 7, orin a string II' coiled round the conductors I, 2 as illustrated in Fig.8.

As represented in Figs. 6 to 8, the securing 45 means may serve also forsupporting a cable sheathing I3 which may be a metal screening activeagainst outer fields'and may be wound around the rings I I, as shown onthe left in Fig. 6, or coiled on the string II". 50

Cables of the novel construction may be combined to form a multiplecable, in such a manner for instance, that onto a cable having a metalsheathing or screening I3, as bef re described, other cables of this ora similar construction are u ,ments thus combine the advantage ofconcentric cables. that is, of having no outer field; with the advantageof two-core cables, which consists in doing away with induction fromwithout, and,

' as regards the current distribution, are superior to the customaryarrangements of high frequency cables.

What is claimed is:

1. A high frequency cable having strap sh'aped conductors intersectinglengthwise at right angles wherein the conductors are slotted and one ofthem is made in two parts assembled in the slots of the other conductor.1

2. A cable in accordance with claim 1 wherein insulating rings arearranged on the conductors for securing them in their mutual position.

3. A high frequency cable according to claim 1 wherein insulating meansis positioned around said conductors for securing them in their mutual Iposition.

4. A high frequency cable according to claim 1 wherein an insulatingstring is coiled around said conductors for securing them in theirmutual position.

'5. A high frequency cable according to claim 1 wherein insulatingmeans'is positioned around said conductors for securing them in theirmutual position and a metal sheathing. encircles said conductors and issupportedpbyssaid insulating means.

WALTER MAX HAHNEMANN.

